Prostate-Specific Membrane Antigen PET/CT Combined with Sentinel Node Biopsy for Primary Lymph Node Staging in Prostate Cancer

Feasibility of Using a Novel Drop-In Gamma Probe for 99mTc-PSMA-I&S-Guided Lymph Node Detection During Robot-Assisted Radical Prostatectomy for Primary Prostate Cancer

PURPOSE

Prostate-specific membrane antigen (PSMA)-targeted radioguided surgery (RGS) has gained increased interest in prostate cancer (PCa). This analysis aims to evaluate the feasibility, safety, and limitations of RGS with a novel drop-in gamma probe in primary PCa.

PATIENTS AND METHODS

The data of 13 patients with primary PCa undergoing RGS were analyzed retrospectively. After preoperative administration of 99mTc-PSMA-I&S, a SPECT/CT was conducted and a robotic radical prostatectomy was performed the following day including intraoperative assessment of the lymph node stations using a novel robotic drop-in gamma probe. This was followed by an extended pelvic lymph node dissection (ePLND) with ex vivo control measurement using the drop-in and a conventional rigid gamma probe.

RESULTS

Eleven patients (median PSA value of 11 ng/mL) had high-risk and 2 patients had intermediate-risk PCa. Overall, a median of 22 ePLND lymph nodes were dissected. In 1 patient, preoperative SPECT/CT imaging showed suspicious lymph nodes, which could be confirmed intraoperatively with the robotic drop-in probe and subsequently in the final histopathological analysis. RGS failed to identify 2 patients with micrometastases (<3 mm) preoperatively and intraoperatively. No postoperative complications related to 99mTc-PSMA-I&S RGS or ePLND occurred.

CONCLUSIONS

RGS with the novel drop-in gamma probe and 99mTc-PSMA-I&S allows for a reliable intraoperative screening for lymph node metastases in robot-assisted radical prostatectomy for primary PCa with an acceptable safety profile. However, limitations in the detection of micrometastases need to be overcome before omitting extended ePLND in patients at risk for lymphatic spread.

A systematic review and meta-analysis to evaluate the diagnostic accuracy of PSMA PET/CT in the initial staging of prostate cancer

BACKGROUND

Positron Emission Tomography-Computed Tomography using Prostate-Specific Membrane Antigen (PSMA PET/CT) is notable for its superior sensitivity and specificity in detecting recurrent PCa and is under investigation for its potential in pre-treatment staging. Despite its established efficacy in nodal and metastasis staging in trial setting, its role in primary staging awaits fuller validation due to limited evidence on oncologic outcomes. This systematic review and meta-analysis aims to appraise the diagnostic accuracy of PSMA PET/CT compared to CI for comprehensive PCa staging.

METHODS

Medline, Scopus and Web of science databases were searched till March 2023. Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were followed to identify eligible studies. Primary outcomes were specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV) of PSMA PET/CT for local, nodal and metastatic staging in PCa patients. Due to the unavailability of data, a meta-analysis was feasible only for detection of seminal vesicles invasion (SVI) and LNI.

RESULTS

A total of 49 studies, comprising 3876 patients, were included. Of these, 6 investigated accuracy of PSMA PET/CT in detection of SVI. Pooled sensitivity, specificity, PPV and NPV were 42.29% (95%CI: 29.85-55.78%), 87.59% (95%CI: 77.10%-93.67%), 93.39% (95%CI: 74.95%-98.52%) and 86.60% (95%CI: 58.83%-96.69%), respectively. Heterogeneity analysis revealed significant variability for PPV and NPV. 18 studies investigated PSMA PET/CT accuracy in detection of LNI. Aggregate sensitivity, specificity, PPV and NPV were 43.63% (95%CI: 34.19-53.56%), 85.55% (95%CI: 75.95%-91.74%), 67.47% (95%CI: 52.42%-79.6%) and 83.61% (95%CI: 79.19%-87.24%). No significant heterogeneity was found between studies.

CONCLUSIONS

The present systematic review and meta-analysis highlights PSMA PET-CT effectiveness in detecting SVI and its good accuracy in LNI compared to CI. Nonetheless, it also reveals a lack of high-quality research on its performance in clinical T staging, extraprostatic extension and distant metastasis evaluation, emphasizing the need for further rigorous studies.

Continuous innovation in precision radio-guided surgery

Since its origins, nuclear medicine has faced technological changes that led to modifying operating modes and adapting protocols. In the field of radioguided surgery, the incorporation of preoperative scintigraphic imaging and intraoperative detection with the gamma probe provided a definitive boost to sentinel lymph node biopsy to become a standard procedure for melanoma and breast cancer. The various technological innovations and consequent adaptation of protocols come together in the coexistence of the disruptive and the gradual. As obvious examples we have the introduction of SPECT/CT in the preoperative field and Drop-in probes in the intraoperative field. Other innovative aspects with possible application in radio-guided surgery are based on the application of artificial intelligence, navigation and telecare.

PSMA PET/CT for Primary Staging of Prostate Cancer - An Updated Overview

Prostate-specific membrane antigen PET/CT for primary staging of prostate cancer is becoming increasingly popular due to simultaneous assessment of whole-body disease burden, with superior sensitivity and specificity for detecting metastases compared to conventional imaging. PSMA PET in combination with multiparametric MRI (mpMRI) improves the sensitivity of assessment of extra-prostatic extension and seminal vesicle invasion compared to mpMRI alone, and may serve as a second line modality for image-guided biopsy in selected patients with negative mpMRI and/or negative primary biopsies. The superior diagnostic accuracy of PSMA PET/CT affects clinical decision-making with a change of clinical management in one-fourth of patients compared to conventional imaging. However, at present, the effect of implementing PSMA PET/CT for primary staging on patient outcomes is not clear, and prospective studies are warranted. There are several PSMA tracers with similar performance and minor individual pharmacokinetic differences such as higher rate of unspecific bone uptake with 18F-PSMA-1007, but on the other hand, lower urinary excretion, which could give an advantage in the detection of local recurrence. Proper training of the reporting physicians and knowledge of the pitfalls of the specific PSMA tracer used is of utmost importance for high-quality reading. We aim to provide an overview of the current literature and an update on the status of PSMA PET/CT for primary staging of prostate cancer.

The sentinel node with technetium-99m for prostate cancer. A safe and mature new gold standard?

BACKGROUND

The objective was to carry out a prospective study to compare the current extended pelvic lymph node dissection (ePLND) to the sentinel node (SN) technique with 99mTcnanocolloid.

METHODS

We conducted a prospective study between January 2013 and May 2020. In the first 74 patients, 99mTc-nanocolloid was used. Then from June 2017 onwards, in 38 patients we used a combined radiotracer prepared by adding indocyanine green (ICG). A preoperative SPECT/CT was also performed to check on the SNs. We extracted the SNs guided by a laparoscopic gamma-ray detection probe and/or a fluorescence camera.

RESULTS

We included 112 patients with a Briganti nomogram-assessed risk of 5% or more. In 4 out of the total, the radiotracer did not migrate. The mean number of extracted nodes was 21.56 (13.46-29.71) and the mean of extracted SNs was 5.17 (1.83-8.51) (P<0.001). The technique that registered the most nodes with high activity was SPECT/CT, with an average of 4.33 nodes (2.42-6.23) (P<0.001). We found SNs outside the template in 78% of the patients. A total of 46% of the complications were related to ePLND. The SN biopsy showed a sensitivity of 100%, specificity of 97.5%, PVV of 92.86%, and NPV of 100%.

CONCLUSIONS

Our results prove that ePLND is a technique with significant morbidity; up to 46% of the complications were related to the ePLND. The SN surgery showed great accuracy in detecting metastases due to the SPECT/CT and a lower rate of complications than ePLND.

Clinical practice in prostate PET imaging

Positron emission tomography (PET) imaging in prostate cancer has advanced significantly in the past decade with prostate cancer targeted radiopharmaceuticals now playing a growing role in diagnosis, staging, and treatment. This narrative review focuses on the most commonly used PET radiopharmaceuticals in the USA: prostate-specific membrane antigen (PSMA), fluciclovine, and choline. 18F-fluorodeoxyglucose (FDG) is used in many other malignancies, but rarely in prostate cancer. Previous literature is discussed regarding each radiopharmaceutical's utility in the settings of screening/diagnosis, initial staging, biochemical recurrence, advanced disease, and evaluation prior to targeted radiopharmaceutical therapy and radiation therapy. PET imaging has demonstrated utility over traditional imaging in various scenarios; however, there are few head-to-head studies comparing PET radiopharmaceuticals. PSMA radiopharmaceuticals are the newest tracers developed and have unique properties and uses, especially at low prostate-specific antigen (PSA) levels. However, each PET radiopharmaceutical has different properties which can affect image interpretation. Choline and fluciclovine have minimal urinary activity, whereas PSMA agents can have high urinary activity which may affect locoregional disease evaluation. Of the three radiopharmaceuticals, only PSMA is approved for both diagnostic and therapeutic indications with 177Lu-PSMA. A variety of diagnostic PET radiotracers for prostate cancer allows for increased flexibility, especially in the setting of supply chain and medication shortages. For the time being, keeping a diverse group of PET radiopharmaceuticals for prostate cancer is justifiable.

The Diagnostic Value of the Sentinel Node Procedure to Detect Occult Lymph Node Metastases in PSMA PET/CT Node-Negative Prostate Cancer Patients

Our objective was to assess the diagnostic value of the sentinel node (SN) procedure for lymph node staging in primary intermediate- and high-risk prostate cancer patients with node-negative results on prostate-specific membrane antigen PET/CT (miN0). Methods: From 2016 to 2022, 154 patients with primary, miN0 PCa were retrospectively included. All patients had a Briganti nomogram-assessed nodal risk of more than 5% and underwent a robot-assisted SN procedure for nodal staging. The prevalence of nodal metastases at histopathology and the occurrence of surgical complications according to the Clavien-Dindo classification were evaluated. Results: The SN procedure yielded 84 (14%) tumor-positive lymph nodes with a median metastasis size of 3 mm (interquartile range, 1-4 mm). In total, 55 patients (36%) were reclassified as pN1. A complication of Clavien-Dindo grade 3 or higher occured in 1 patient (0.6%). Conclusion: The SN procedure classified 36% of patients with miN0 prostate cancer with an elevated risk of nodal metastases as pN1.

A Systematic Review of New Imaging Technologies for Robotic Prostatectomy: From Molecular Imaging to Augmented Reality

New imaging technologies play a pivotal role in the current management of patients with prostate cancer. Robotic assisted radical prostatectomy (RARP) is a standard of care for localized disease and through the already imaging-based console subject of research towards combinations of imaging technologies and RARP as well as their impact on surgical outcomes. Therefore, we aimed to provide a comprehensive analysis of the currently available literature for new imaging technologies for RARP. On 24 January 2023, we performed a systematic review of the current literature on Pubmed, Scopus and Web of Science according to the PRISMA guidelines and Oxford levels of evidence. A total of 46 studies were identified of which 19 studies focus on imaging of the primary tumor, 12 studies on the intraoperative tumor detection of lymph nodes and 15 studies on the training of surgeons. While the feasibility of combined approaches using new imaging technologies including MRI, PSMA-PET CT or intraoperatively applied radioactive and fluorescent dyes has been demonstrated, the prospective confirmation of improvements in surgical outcomes is currently ongoing.

Sentinel Lymph Node Biopsy in Prostate Cancer: An Overview of Diagnostic Performance, Oncological Outcomes, Safety, and Feasibility

Sentinel node biopsy (SNB) for prostate cancer (PCa) represents an innovative technique aimed at improving nodal staging accuracy. The routinary adoption of this procedure in patients undergoing radical prostatectomy (RP) might be crucial to identify candidates who could effectively benefit from extensive pelvic lymph nodal dissection (ePLND). Despite some promising results, SNB for PCa is still considered experimental due to the lack of solid evidence and procedural standardization. In this regard, our narrative review aimed to analyze the most recent literature in this field, providing an overview of both the diagnostic accuracy measures and the oncological outcomes of SNB.

Lymphatic mapping for image-guided radiotherapy in patients with locally advanced uterine cervical cancer: a feasibility study

BACKGROUND

Lymph node metastasis is an important prognostic factor in locally advanced cervical cancer (LACC). No imaging method can successfully detect all (micro)metastases. This may result in (lymph node) recurrence after chemoradiation. We hypothesized that lymphatic mapping could identify nodes at risk and if radiation treatment volumes are adapted based on the lymphatic map, (micro)metastases not shown on imaging could be treated. We investigated the feasibility of lymphatic mapping to image lymph nodes at risk for (micro)metastases in LACC and assessed the radiotherapy dose on the nodes at risk.

METHODS

Patients with LACC were included between July 2020 and July 2022. Inclusion criteria were: ≥ 18 years old, intended curative chemoradiotherapy, investigation under anesthesia. Exclusion criteria were: pregnancy and extreme obesity. All patients underwent abdominal MRI, [¹⁸F]FDG-PET/CT and lymphatic mapping after administration of 6-8 depots of ^99mTc]Tc-nanocolloid followed by planar and SPECT/CT images 2-4 and 24 h post-injection.

RESULTS

Seventeen patients participated. In total, 40 nodes at risk were visualized on the lymphatic map in 13/17 patients with a median of two [range 0-7, IQR 0.5-3] nodes per patient, with unilateral drainage in 4/13 and bilateral drainage in 9/13 patients. No complications occurred. The lymphatic map showed more nodes compared to suspicious nodes on MRI or [¹⁸F]FDG-PET/CT in 8/14 patients. Sixteen patients were treated with radiotherapy with 34 visualized nodes on the lymphatic map. Of these nodes, 20/34 (58.8%) received suboptimal radiotherapy: 7/34 nodes did not receive radiotherapy at all, and 13/34 received external beam radiotherapy (EBRT), but no simultaneous integrated boost (SIB).

CONCLUSION

Lymphatic mapping is feasible in LACC. Almost 60% of nodes at risk received suboptimal treatment during chemoradiation. As treatment failure could be caused by (micro)metastasis in some of these nodes, including nodes at risk in the radiotherapy treatment volume could improve radiotherapy treatment outcome in LACC. Trail registration The study was first registered at the International Clinical Trial Registry Platform (ICTRP) under number of NL9323 on 4 March 2021. Considering the source platform was not operational anymore, the study was retrospectively registered again on February 27, 2023 at CilicalTrials.gov under number of NCT05746156.

The Sentinel Lymph Node in Treatment Planning: A Narrative Review of Lymph-Flow-Guided Radiotherapy

The sentinel lymph node technique is minimally invasive and used routinely by surgeons, reducing the need for morbid extensive lymph node dissections, which is a significant advantage for cancer staging and treatment decisions. The sentinel lymph node could also help radiation oncologists to identify tumor drainage for each of their patients, leading to a more personalized radiotherapy, instead of a probabilistic irradiation based on delineation atlases. The aim is both to avoid recurrence in unexpected areas and to limit the volume of irradiated healthy tissues. The aim of our study is to evaluate the impact of sentinel lymph node mapping for radiation oncologists. This concept, relying on sentinel lymph node mapping for treatment planning, is known as lymph-flow-guided radiotherapy. We present an up-to-date narrative literature review showing the potential applications of the sentinel lymph node technique for radiotherapy, as well as the limits that need to be addressed before its routine usage.

Sentinel Lymph Node Techniques in Urologic Oncology: Current Knowledge and Application

Lymph node (LN) metastases have a significant negative impact on the prognosis of urological malignancies. Unfortunately, current imaging modalities are insufficient when it comes to detecting micrometastases; thus, surgical LN removal is commonly used. However, there is still no established ideal lymph node dissection (LND) template, leading to unnecessary invasive staging and the possibility of missing LN metastases located outside the standard template. To address this issue, the sentinel lymph node (SLN) concept has been proposed. This technique involves identifying and removing the first group of draining LNs, which can accurately stage cancer. While successful in breast cancer and melanoma, the SLN technique in urologic oncology is still considered experimental due to high false-negative rates and lack of data in prostate, bladder, and kidney cancer. Nevertheless, the development of new tracers, imaging modalities, and surgical techniques may improve the potential of the SLN procedures in urological oncology. In this review, we aim to discuss the current knowledge and future contributions of the SLN procedure in the management of urological malignancies.

Clinical advancement of precision theranostics in prostate cancer

Theranostic approaches with positron emission tomography/computed tomography (PET/CT) or PET/magnetic resonance imaging (PET/MRI) molecular imaging probes are being implemented clinically in prostate cancer (PCa) diagnosis and imaging-guided precision surgery. This review article provides a comprehensive summary of the rapidly expanding list of molecular imaging probes in this field, including their applications in early diagnosis of primary prostate lesions; detection of lymph node, skeletal and visceral metastases in biochemical relapsed patients; and intraoperative guidance for tumor margin detection and nerve preservation. Although each imaging probe shows preferred efficacy in some applications and limitations in others, the exploration and research efforts in this field will eventually lead to improved precision theranostics of PCa.

The application of indocyanine green in guiding prostate cancer treatment

Objective

Indocyanine green (ICG) with near-infrared fluorescence absorption is approved by the United States Food and Drug Administration for clinical applications in angiography, blood flow evaluation, and liver function assessment. It has strong optical absorption in the near-infrared region, where light can penetrate deepest into biological tissue. We sought to review its value in guiding prostate cancer treatment.

Methods

All related literature at PubMed from January 2000 to December 2020 were reviewed.

Results

Multiple preclinical studies have demonstrated the usefulness of ICG in identifying prostate cancer by using different engineering techniques. Clinical studies have demonstrated the usefulness of ICG in guiding sentinel node dissection during radical prostatectomy, and possible better preservation of neurovascular bundle by identifying landmark prostatic arteries. New techniques such as adding fluorescein in additional to ICG were tested in a limited number of patients with encouraging result. In addition, the use of the ICG was shown to be safe. Even though there are encouraging results, it does not carry sufficient sensitivity and specificity in replacing extended pelvic lymph node dissection during radical prostatectomy.

Conclusion

Multiple preclinical and clinical studies have shown the usefulness of ICG in identifying and guiding treatment for prostate cancer. Larger randomized prospective studies are warranted to further test its usefulness and find new modified approaches.

Pelvic lymph node dissection in prostate and bladder cancers

Prostate cancer and bladder cancer accounts for approximately 13.5% and 3% of all male cancers and all newly diagnosed cancers (regardless sex), respectively. Thus, these cancers represent a major health and economic burden globally. The knowledge of lymph node status is an integral part of the management of any solid tumor. In the urological field, pelvic lymph node dissection (PLND) is of paramount importance in the diagnosis, management, and prognosis of prostate and bladder cancers. However, PLND may be associated with several comorbidities. In this narrative review, the most recent updates concerning the patterns and incidence of lymph node metastasis, the role of different imaging studies and nomograms in determining patients' eligibility for PLND, and the anatomical templates of PLND in urologic patients with bladder or prostate cancer will be discussed.

Incorporating Prostate-specific Membrane Antigen Positron Emission Tomography in Management Decisions for Men with Newly Diagnosed or Biochemically Recurrent Prostate Cancer

CONTEXT

Prostate-specific membrane antigen (PSMA) is a promising molecular target for prostate cancer (PCa) that has allowed the development of a novel diagnostic approach to PCA in the primary and recurrent settings.

OBJECTIVE

To summarize available data and recommendations regarding the use of PSMA in newly diagnosed and recurrent PCa via a narrative review.

EVIDENCE ACQUISITION

A literature review was conducted using MEDLINE (via PubMed) and Scopus. The search strategy included meta-analyses, reviews, and original studies on staging and restaging with ⁶⁸Ga-PSMA positron emission tomography (PET)/computed tomography (CT).

EVIDENCE SYNTHESIS

Studies comparing PSMA-targeted imaging and conventional imaging suggest superior performance of PSMA-targeted imaging in primary and recurrent PCa, albeit with several clinically relevant limitations. Pretreatment ⁶⁸Ga-PSMA PET/CT allowed more accurate PCa staging in compared to routine practice for high-risk cases, and identified a number of otherwise unknown metastatic lesions. In biochemically recurrent PCa, PSMA PET can reveal sites of recurrence with greater sensitivity and specificity than conventional imaging, potentially detecting a major proportion of occult disease. This review will help providers in applying the most up-to-date and relevant literature to (1) determine which patients truly have oligometastatic disease and (2) ascertain who is most likely to experience a meaningful response to local consolidation in the biochemical recurrence setting.

CONCLUSIONS

Data on PSMA diagnostic studies in primary and recurrent PCa highlight the accuracy and clinical application of PSMA PET. While this review and the evidence to date might lead to a perception of superiority in metastasis directed therapy, fundamental lack of phase III clinical trials with clinically meaningful outcomes are yet to be determined.

PATIENT SUMMARY

PSMA (prostate-specific membrane antigen) scans have shown great promise for initial evaluation of prostate cancer (PCa) and in detection of PCa recurrence. The benefits are more apparent for initial staging of PCa. There are more limited clinical trial results for PCa recurrence on how best to use this new technique to guide cancer treatment.

A nomogram for accurately predicting the pathological upgrading of prostate cancer, based on 68 Ga-PSMA PET/CT

PURPOSE

To develop and validate a nomogram for preoperative predicting the pathological upgrading of prostate cancer (PCa).

METHODS

The prediction model was developed in a primary cohort that consisted of 208 PCa patients. All patients included in the study possessed both biopsy pathology specimens and radical prostatectomy pathology specimens, and completed the (⁶⁸ Ga-prostate-specific membrane antigen [PSMA]) positron emission tomography/computed tomography (PET/CT) detection. The R function "createDataPartition" was used in a 7:3 ratio to randomly divide the patients into training and validation cohorts. In the training cohort, the independent predictors of pathological upgrading of PCa were determined by univariate analysis, univariate regression analysis and multivariate regression analysis. Based on these independent predictors, a nomogram was developed, and its performance was evaluated by receiver operating characteristic (ROC) curve, area under the curve (AUC) and calibration curve of training cohort and validation cohort.

RESULTS

The nomogram incorporated five independent predictors including prostate volume (PV), SUV_max of the ⁶⁸ Ga-PSMA PET/CT examination on prostate lesions (SUV_max ), body mass index (BMI); percentage of cancer positive biopsy cores (PPC) and biopsy International Society of Urological Pathology (ISUP) grade. The nomogram showed good diagnostic accuracy for the pathological upgrading of both the training cohort and the validation cohort (AUC = 0.818 and 0.806, respectively). The calibration curves for the two cohorts both showed optimal agreement between nomogram prediction and actual observation.

CONCLUSIONS

We developed and validated a nomogram to accurately predict the risk of pathological upgrading after radical PCa surgery, which can provide accurate basis for therapeutic schedule and prognostic data of PCa patients.

Robot-assisted Prostate-specific Membrane Antigen-radioguided Salvage Surgery in Recurrent Prostate Cancer Using a DROP-IN Gamma Probe: The First Prospective Feasibility Study

BACKGROUND

It has been proven that intraoperative prostate-specific membrane antigen (PSMA)-targeted radioguidance is valuable for the detection of prostate cancer (PCa) lesions during open surgery. Rapid extension of robot-assisted, minimally invasive surgery has increased the need to make PSMA-radioguided surgery (RGS) robot-compliant.

OBJECTIVE

To evaluate whether the miniaturized DROP-IN gamma probe facilitates translation of PSMA-RGS to robotic surgery in men with recurrent PCa.

DESIGN, SETTING, AND PARTICIPANTS

This prospective feasibility study included 20 patients with up to three pelvic PCa recurrences (nodal or local) on staging PSMA positron emission tomography (PET) after previous curative-intent therapy.

SURGICAL PROCEDURE

Robot-assisted PSMA-RGS using the DROP-IN gamma probe was carried out 19-23 h after intravenous injection of ^99mtechnetium PSMA-Investigation & Surgery (^99mTc-PSMA-I&S).

MEASUREMENTS

The primary endpoint was the feasibility of robot-assisted PSMA-RGS. Secondary endpoints were a comparison of the radioactive status (positive or negative) of resected specimens and final histopathology results, prostate-specific antigen (PSA) response following PSMA-RGS, and complications according to the Clavien-Dindo classification.

RESULTS AND LIMITATIONS

Using the DROP-IN probe, 19/21 (90%) PSMA-avid lesions could be resected robotically. On a per-lesion basis, the sensitivity and specificity of robot-assisted PSMA-RGS was 86% and 100%, respectively. A prostate-specific antigen (PSA) reduction of >50% and a complete biochemical response (PSA <0.2 ng/ml) were seen in 12/18 (67%) and 4/18 (22%) patients, respectively. During follow-up of up to 15 mo, 4/18 patients (22%) remained free of biochemical recurrence (PSA ≤0.2 ng/ml). One patient suffered from a Clavien-Dindo grade >III complication.

CONCLUSIONS

The DROP-IN probe helps in realizing robot-assisted PSMA-RGS. The procedure is technically feasible for intraoperative detection of nodal or local PSMA-avid PCa recurrences.

PATIENT SUMMARY

A device called the DROP-IN probe facilitates minimally invasive, robot-assisted surgery guided by radioactive tracers in patients with recurrent prostate cancer. This procedure holds promise for improving the intraoperative identification and removal of prostate cancer lesions.

Can Negative Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography Avoid the Need for Pelvic Lymph Node Dissection in Newly Diagnosed Prostate Cancer Patients? A Systematic Review and Meta-analysis with Backup Histology as Reference Standard

CONTEXT

The role of positron emission tomography/computed tomography (PET/CT) with prostate-specific membrane antigen (PSMA) in the primary staging for patients with prostate cancer (PCa) is still debated.

OBJECTIVE

To analyze published studies reporting the accuracy of PSMA PET/CT for detecting lymph node invasion (LNI) at pelvic lymph node dissection (PLND).

EVIDENCE ACQUISITION

A search of PubMed/MEDLINE, Cochrane library's Central, EMBASE and Scopus databases, from inception to May 2021, was conducted. The primary outcome was to evaluate the sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of PSMA PET/CT in detecting LNI on a per-patient level. As a secondary outcome, NPV of PET PSMA was tested on a per-node-level analysis. Detection rates were pooled using random-effect models. Preplanned subgroup analyses tested the diagnostic accuracy after stratification for the preoperative risk group. PPV and NPV variation over LNI prevalence was evaluated. Only studies including extended PLND (ePLND) as the reference standard test were included.

EVIDENCE SYNTHESIS

Twenty-seven studies, with a total of 2832 participants, were included in quantitative synthesis. The sensitivity, specificity, PPV, and NPV of PSMA PET/CT for LNI were, respectively, 58% (95% confidence interval [CI] 50-66%), 95% (95% CI 93-97%), 79% (95% CI 72-85%), and 87% (95% CI 84-89%), with overall moderate heterogeneity between studies. At bivariate analysis, the diagnostic accuracy of PSMA PET/CT estimated through summary receiver operating characteristic-derived area under the curve was 84% (95% CI 81-87%). On a per-node level, NPV of PET PSMA was 97% (95% CI 96-99%). At subgroup analyses, according to preoperative risk groups, sensitivity, specificity, PPV, and NPV were 51%, 93%, 73%, and 81%, respectively, in high-risk patients. Over the LNI prevalence range of 5-40%, PPV increased from 59% to 91%, while NPV decreased from 99% to 84%.

CONCLUSIONS

PSMA PET/CT scan provides promising accuracy in the field of primary nodal staging for PCa. The high NPV in men with a lower risk of LNI might be clinically useful to reduce the number of unnecessary PLND procedures performed. Conversely, in high-risk patients, negative PSMA PET/CT cannot replace staging ePLND.

PATIENT SUMMARY

In this systematic review and meta-analysis, we demonstrated that prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) scan may optimize the primary nodal staging and surgical management of prostate cancer patients candidate to radical prostatectomy. The high negative predictive value in men with a lower risk of lymph node invasion might be clinically useful for reducing the number of useless pelvic lymph node dissection (PLND) procedures performed. Conversely, in high-risk patients, negative PSMA PET/CT cannot allow avoiding of PLND.

Implementation of radioguided surgery in prostate cancer

With the development of new imaging technologies and tracers, the applications of radioguided surgery for prostate cancer are growing rapidly. The current paper aims to give an overview of the recent advances of radioguided surgery in the management of prostate cancer. We performed a literature search to give an overview of the current status of radioguided surgery for prostate cancer. Three modalities of radioguided surgery, the sentinel node procedure, Cerenkov Luminescence / beta-radio-guided surgery and radio-guided salvage surgery in recurrent prostate cancer, were reviewed in detail. Radioguided surgery for prostate cancer has shown promising value in the treatment of primary diagnosed prostate cancer and recurrent loco-regional lymph node positive prostate cancer. Advances have been made into minimal invasive (robot-assisted) laparoscopic surgery. The sentinel node procedure for prostate cancer has been further developed and is currently performed with high diagnostic sensitivity. Cerenkov luminescence imaging is a feasible and encouraging technique for intraoperative margin assessment in prostate cancer. Radioguided surgery in recurrent prostate cancer has shown to be feasible, yielding high sensitivity and specificity for detecting small local recurrences and metastases. With the availability of different new tracers, the road has been paved towards clinically feasible radioguided surgery for prostate cancer. Novel technologies now being developed for minimal invasive surgery are speeding up clinical research. Currently, none of the radioguided surgery techniques mentioned have been accepted as standard of care.

Prostate-Specific Membrane Antigen PET for Assessment of Primary and Recurrent Prostate Cancer with Histopathology as Reference Standard: A Systematic Review and Meta-Analysis

Prostate-specific membrane antigen PET is a promising diagnostic tool in prostate cancer. The gold standard for the detection of prostate tumor and lymph node metastases is histopathology. The aim of the present review was to investigate accuracy measures of ⁶⁸Ga/¹⁸F-labeled prostate-specific membrane antigen PET tracers in primary and recurrent prostate cancer with systematic sector-based histopathology as the reference standard. A systematic literature search was performed and 34 studies were included. Overall, prostate-specific membrane antigen PET showed high specificity, but variable sensitivity to localize known prostate cancer and detect pelvic lymph node metastases.

Use of intraoperative fluorescence to enhance robot-assisted radical prostatectomy

Robot-assisted radical prostatectomy has become the standard of care for the removal of localized prostate cancer. Positive outcomes depend upon the precise removal of the prostate and associated tissue without damage to nearby structures. This process can be aided by fluorescence-guided surgery to enhance the visual contrast between different structures. Here the authors have conducted a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify ten investigations into the use of fluorescence-guided surgery in robot-assisted radical prostatectomy. These studies used fluorescent tracers to identify structures, including the prostate, neurovascular bundle and lymph nodes. These studies demonstrate the safe and effective use of fluorescence-guided surgery in robot-assisted radical prostatectomy and pave the way for further developments in this field.

A narrative review of pelvic lymph node dissection in prostate cancer

Pelvic lymph node dissection (PLND) is an important component in the staging and prognostication of prostate cancer. We performed a narrative review to assess the literature surrounding PLND: (I) the current guideline recommendations and contemporary utilization, (II) the calculation of patient-specific risk to perform PLND using available nomograms, (III) to review the extent of dissection, and its associated outcomes and complications. Due to the improved lymph node yield, better staging, and theoretical improvement in the control of micro-metastatic disease, guidelines have supported the use of (extended-) PLND in patients deemed to be at intermediate or high risk of lymph node involvement (often at a threshold of 5% on modern risk nomograms). However, in practice, real-world utilization of PLND varies considerably due to multiple reasons. Conflicting evidence persists with no clear oncological benefit to PLND, and a small, but important, risk of morbidity. Complications are rare, but include lymphoceles; thromboembolic events; and more rarely, obturator nerve, vascular, and ureteric injury. Furthermore, changing disease incidence and stage migration in the context of earlier detection overall have led to a decreased risk of nodal disease. The trade-offs between the benefits, harms, and risk tolerance/threshold must be carefully considered between each patient and their clinician.

A DROP-IN Gamma Probe for Robot-assisted Radioguided Surgery of Lymph Nodes During Radical Prostatectomy

BACKGROUND

The DROP-IN gamma probe was introduced to overcome the restricted manoeuvrability of traditional laparoscopic gamma probes. Through enhanced manoeuvrability and surgical autonomy, the DROP-IN promotes the implementation of radioguided surgery in the robotic setting.

OBJECTIVE

To confirm the utility and safety profile of the DROP-IN gamma probe and to perform a comparison with the traditional laparoscopic gamma probe and fluorescence guidance.

DESIGN, SETTING, AND PARTICIPANTS

Twenty-five prostate cancer patients were scheduled for a robot-assisted sentinel lymph node (SN) procedure, extended pelvic lymph node dissection, and prostatectomy at a single European centre.

SURGICAL PROCEDURE

After intraprostatic injection of indocyanine green (ICG)-^99mTc-nanocolloid (n = 12) or ^99mTc-nanocolloid + ICG (n = 13), SN locations were defined using preoperative imaging. Surgical excision of SNs was performed under image guidance using the DROP-IN gamma probe, the traditional laparoscopic gamma probe, and fluorescence imaging.

MEASUREMENTS

Intraoperative SN detection was assessed for the different modalities and related to anatomical locations. Patient follow-up was included (a median of 18 mo).

RESULTS AND LIMITATIONS

Overall, 47 SNs were pursued in vivo by the DROP-IN gamma probe, of which 100% were identified. No adverse events related to its use were observed. In vivo fluorescence imaging identified 91% of these SNs. The laparoscopic gamma probe identified only 76% of these SNs, where the detection inaccuracies appeared to be related to specific anatomical regions.

CONCLUSIONS

Owing to improved manoeuvrability, the DROP-IN probe yielded improved SN detection rates compared with the traditional gamma probe and fluorescence imaging. These findings underline that the DROP-IN technology provides a valuable tool for radioguided surgery in the robotic setting.

PATIENT SUMMARY

Radioguided robot-assisted surgery with the novel DROP-IN gamma probe is feasible and safe. It enables more efficient intraoperative identification of sentinel lymph nodes than can be achieved with a traditional laparoscopic gamma probe. The use of the DROP-IN probe in combination with fluorescence imaging allows for a complementary optical confirmation of node localisations.

Sentinel Node Imaging and Radioguided Surgery in the Era of SPECT/CT and PET/CT: Toward New Interventional Nuclear Medicine Strategies

We review recent technological advances and new clinical indications for sentinel node (SN) and radioguided surgery in order to delineate future tendencies of interventional nuclear medicine in this field. A literature research was performed in PubMed to select relevant articles to be used as key references for analysis of the current approaches and tendencies in SN and radioguided surgery, as well as the evolving contribution of nuclear medicine intervention techniques to the various clinical applications. For classic indications such as melanoma and breast cancer, the incorporation of the SN approach based on the combined use of existing and new preoperative and intraoperative technologies in high-risk patient categories is becoming an emerging area of clinical indication. For SN biopsy staging in other malignancies with more complex lymphatic drainage, the incorporation of sophisticated tools is most helpful. The consecutive use of PET/CT and the SN procedure is increasing as a potential combined approach for the management of specific areas such as the axilla and the pelvis in patients at high risk of regional dissemination. Also, for the management of locoregional metastasis and oligometastatic disease, interventional nuclear medicine techniques are becoming valuable alternatives. The extended experience with SN biopsy is leading to technological advances facilitating the incorporation of this procedure to stage other malignancies with complex lymphatic drainage. New nuclear medicine-based approaches, incorporating SPECT/CT and PET/CT to guide resection of SNs and occult metastases, have recently been gaining ground.

Near-infrared fluorescence imaging compared to standard sentinel lymph node detection with blue dye in patients with vulvar cancer - a randomized controlled trial

OBJECTIVE

The aim of this study was to assess the superiority of ICG-^99mTc-nanocolloid for the intraoperative visual detection of sentinel lymph nodes (SLNs) in vulvar squamous cell carcinoma (VSCC) patients compared to standard SLN detection using ^99mTc-nanocolloid with blue dye.

METHODS

In this multicenter, randomized controlled trial, VSCC patients underwent either the standard SLN procedure or with the hybrid tracer ICG-^99mTc-nanocolloid. The primary endpoint was the percentage of fluorescent SLNs compared to blue SLNs. Secondary endpoints were successful SLN procedures, surgical outcomes and postoperative complications.

RESULTS

Forty-eight patients were randomized to the standard (n = 24) or fluorescence imaging group (n = 24) using ICG-^99mTc-nanocolloid. The percentage of blue SLNs was 65.3% compared to 92.5% fluorescent SLNs (p < 0.001). A successful SLN procedure was obtained in 92.1% of the groins in the standard group and 97.2% of the groins in the fluorescence imaging group (p = 0.33). Groups did not differ in surgical outcome, although more short-term postoperative complications were documented in the standard group (p = 0.041).

CONCLUSIONS

Intraoperative visual detection of SLNs in patients with VSCC using ICG-^99mTc-nanocolloid was superior compared to ^99mTc-nanocolloid and blue dye. The rate of successful SLN procedures between both groups was not significantly different. Fluorescence imaging has potential to be used routinely in the SLN procedure in VSCC patients to facilitate the search by direct visualization.

CLINICAL TRIAL REGISTRATION

Netherlands Trial Register (Trial ID NL7443).

Prostate specific membrane antigen positron emission tomography/computed tomography and staging high risk prostate cancer: a non-systematic review of high clinical impact literature

INTRODUCTION

Prostate specific membrane antigen (PSMA) positron emission tomography (PET) with computed tomography (CT) is a promising molecular imaging technique for prostate cancer (PCa). Although not yet included in international guidelines, PSMA PET/CT is commonly used in clinical practice to stage patients with newly diagnosed PCa. This review focuses on the most up-to-date literature on staging high-risk prostate cancer with PSMA PET/CT.

EVIDENCE ACQUISITION

An online based literature research encompassing original studies, reviews and meta-analysis was performed in the month of November of 2019. The most relevant and impactful research was then extracted based on the expertise of the authors, with the specific focus of highlighting the clinical impact and appropriateness of PSMA PET/CT in staging PCa.

EVIDENCE SYNTHESIS

The use of PSMA PET/CT is appropriate in all high-risk patients with newly diagnosed PCa as it will often have a significant clinical impact. Although preliminary findings are promising, there is still a scarcity of data regarding the performance of PSMA PET/CT vs. other modalities in defining disease within the prostate gland. There is good evidence suggesting that PSMA PET/CT may be superior to every other imaging modality in assessing loco-regional and distant metastatic disease.

CONCLUSIONS

PSMA PET/CT has the potential to become a gold standard in staging high risk prostate cancer, providing clinicians with accurate information on the extent of disease within the prostate and the presence of loco-regional and distant metastatic disease within a single scan.

Pelvic lymph node distribution and metastases of prostate and bladder cancer: a systematic literature review and template proposal

PURPOSE

To systematically review the relevant literature that evaluates the LN topographical distribution and propose a uniform template.

METHODS

A bibliographic search of PubMed/Medline, Embase and SCOPUS was performed for studies reporting data of LN imaging and/or nodal resection.

RESULTS

101 and 26 articles met the inclusion criteria for PCa and BCa, respectively. In PCa, the most common locations of positive LNs for surgical and imaging studies were external iliac (both 38 studies), followed by obturator (38 and 37, respectively). Similarly, in BCa, the most common location of positive nodes for surgical and imaging studies were external iliac (19 and 4, respectively), followed by obturator (15 and 3 studies, respectively). In PCa, median percentages of positive external iliac nodes/patient were 12.2% and 11.6% for surgical and imaging studies, respectively while corresponding rates for BCa were 3.9% and 17.6%. There were high risks of bias across studies as well as high heterogeneity in the definition of the anatomic boundaries of lymphadenectomy templates.

CONCLUSIONS

This review highlights the lack of detailed information on exact LN templates and metastases location, which in turn hinders generation of high-quality evidence on optimal lymphadenectomy templates. Our proposed template is applicable for both imaging and surgical description and could facilitate the translation of anatomical location from imaging to surgical resection.

Haute Couture or Ready-to-Wear? Tailored Pelvic Radiotherapy for Prostate Cancer Based on Individualized Sentinel Lymph Node Detection

Prostate cancer (PCa) pelvic radiotherapy fields are defined by guidelines that do not consider individual variations in lymphatic drainage. We examined the feasibility of personalized sentinel lymph node (SLN)-based pelvic irradiation in PCa. Among a SLN study of 202 patients, we retrospectively selected 57 patients with a high risk of lymph node involvement. Each single SLN clinical target volume (CTV) was individually segmented and pelvic CTVs were contoured according to Radiation Therapy Oncology Group (RTOG) guidelines. We simulated a radiotherapy plan delivering 46 Gy and calculated the dose received by each SLN. Among a total of 332 abdominal SLNs, 305 pelvic SLNs (beyond the aortic bifurcation) were contoured (mean 5.4/patient). Based on standard guidelines, CTV missed 67 SLNs (22%), mostly at the common iliac level (40 SLNs). The mean distance between iliac vessels and the SLN was 11mm, and despite a 15mm margin around the iliac vessels, 9% of SLNs were not encompassed by the CTV. Moreover, 42 SLNs (63%) did not receive 95% of the prescribed dose. Despite a consensus on contouring guidelines, a significant proportion of SLNs were not included in the pelvic CTV and did not receive the prescribed dose. A tailored approach based on individual SLN detection would avoid underdosing pelvic lymph nodes that potentially contain tumor cells.